New Page 1

Bluetongue Serotype 8 first appeared in the Netherlands in the Autumn of 2006. Last year it had a devastating affect on sheep farms and on some cattle farms in Belgium, Holland, Germany and France. Fortunately this year there is a vaccine available to protect livestock against the disease. It is a race against time to get vulnerable stock protected before the infected midges become active. Fortunately there has been a good yield of the virus from the companies that are making the vaccine and supplies are being released faster than was originally anticipated.

We have an order list for the vaccine at the surgery and we have already reserved 7,500 doses. The order list is still open and we will be ordering further supplies before the end of May. I understand that the vaccine is quite temperature sensitive so you will need to keep it cold on the farm and only have one vial out of the fridge at the time when it is being used. It would be better if it was administered on its own and not at the same time as other vaccines or treatments. On May 7th DEFRA put in a tender for a further 13 million additional doses of vaccine, the intention is that there will be enough to vaccinate all of the susceptible animals in the country. On the11th June 13 million additional doses of vaccine were ordered from Merial to ensure that all of the orders can be fulfilled. The vaccine from this company comes in 100ml bottles again it is a one ml sub cutaneous dose once for sheep ant twice for cattle this time with an interval of four weeks between injections.

The protection zone was extended each week in May as more vaccine comes into the wholesalers. there was the a delay of nearly a month when there were problems with one batch of vaccine. Now the production of the vaccine seems to be secure again and 2.2 million additional doses are ready for release on the 14th of July. At the moment the boundary extends from Cornwall, through Gloucestershire and Warwickshire up to Yorkshire and includes the parts of South Wales that was a Restricted Zone. The latest change includes Staffordshire and extends up to Selby in Yorkshire The Surveillance Zone remains unchanged. The chances are that we will have the vaccine after the next boundary change. Keep a watch on this page as soon as I know more I will let you know here.

There are 24 different serotypes of the virus that can replicate both in the host animal and the midge that transmits the infection. It is serotype 8 that is active here, the different serotypes vary as to the severity of the disease that they cause. Culicoides imicola is the midge that is the main vector of the virus, the infection has been detected in other species of Culicoides midge. The danger is that once it gets established here it will be found that other midge species that are numerous in colder climates will be able to transmit the disease. It is known that there are over 40 different midge species in Scotland.

When the midge bites an infected animal the virus is able to replicate in the blood of the midge and in the next ruminant animal that it feeds from. Rate of spread depends on the numbers of infected animals and the numbers of active midges and the air temperature The insect numbers increase throughout the summer and autumn months. They are not active in cold conditions and when it is windy.

Bluetongue is difficult to recognize as it shows a variety of symptoms in different species some breeds of sheep seem to be particularly vulnerable, cattle and wild ruminants are reported to show few or no signs when the are affected. Scientists at Pirbright infected sheep and calves with the type 8 serotype under laboratory conditions recently to monitor the course of infection. They indicated that many of the symptoms were mild and could easily be missed.

The disease was first detected here in cattle on a rare breeds farm near Ipswich on September 22nd and four days later fifty miles away in a cow on a farm near Lowestoft. At that time our weather seemed to be coming from the west so the chances are the virus has been here for some time. DEFRA have now declared this as a confirmed outbreak, there are additional movement restrictions in the protection zone

By the 6th June their were one hundred and thirty six affected holdings. Most of these holdings were detected following blood test for animal movements during the three months of the vector Free Period in the winter. So far this year active infection spread by midge bites has not been reported in the UK or anywhere else in Europe.

Bluetongue can be a devastating disease resulting in the death of 70% of susceptible sheep within two weeks. It is difficult to contain, the affected area on the Continent steadily grew last summer. As things are there is nothing to stop the virus spreading throughout the whole country this year. It is estimated that there are 34 million sheep in the UK and it is not known if any of our breeds has a natural resistance to the infection. Surveys last year trapped culicoides midges here through out the winter. It would be wrong to hope that the disease would die off if we had a cold winter. It is difficult to predict the exact impact of the virus spreading here. It might be that in our colder climate with our midges perhaps not best adapted to spread the virus that many animals would only get a small dose of the infection at first and manage themselves to build up a strong immunity before any symptoms were noticed.

Various things have been suggested to limit the spread of infection. Insecticides may help and some of the spot on fly products are thought to give some protection to cattle. This has not been verified, the chances are a midge would be able to bite an infected animal and would then pick up the insecticide so it would not stop transmission of the virus. The latest information is that the spot on treatments kill midges that land on the back of the animal where the drug was applied but are not able to affect midges that bit the legs or head which are the places they usually feed from. It would seem logical to dip sheep to stop midge bites, but there is little information to support the effectiveness of doing this. Our experience with horses and sweet itch, which is an allergic response to culicoides bites is that the insects will not trouble animals if they are housed overnight in the summer between five in the evening and nine in the morning, this might help in some circumstances.

At the end of December DEFRA ordered 22.5 million doses of Bluetongue vaccine from Intervet. Sheep will require one dose and cattle will need two injections to protect them from the disease. There are two adjuvents in the vaccine to make it work so you can expect some swelling at the injection site for up to six weeks, this will particularly apply to goats and Camelids. Under EEC regulations the vaccine can only be used inside the protection zone. the hope is that we will be able to vaccinate more than 80% of vulnerable stock to limit the spread of the virus. This is an ambitious target. Given the late arrival of the vaccine. Cattle tend to act as reservoirs of infection for sheep. It is not until they have had a second dose of vaccine after three weeks that they will stop passing the infection on.

In 2006 only five percent of deer culled in Belgium were shown to have antibodies to Bluetongue. Last year this figure had increased to forty per cent. It will not be possible to effectively vaccinate wild deer in the summer months. In areas where there is a significant deer population it would be better if all farmed ruminants were vaccinated to achieve the required target.

This is the experience of a Belgium Farmer last year reported on the Suffolk Sheep web site.

"Vaccine should first be made available to livestock on the borders of infected zones; this is the advice of Belgium, Suffolk sheep breeder Jan Van Grinderachter, whose own sheep contracted the virus in August 2007.

He warned that in Belgium they suffered just 60 cases in 2006 which escalated to 2,500 infected farms in 2007. It is likely he claims that the same pattern will wreak havoc in the UK’s livestock industry if the vaccine is not used quickly and wisely.

Speaking to some 80 members of he Suffolk Sheep Society at the annual meeting in Derbyshire, last week (28.2.08) he described the devastating affects the disease has had on Belgium livestock farmers.

Jan explained: “Bluetongue is a virus disease, but it needs hosts and vectors – transmitters, the midge is the transmitter. We have a lot to learn, but we can tell you there are 24 types of bluetongue serotypes, we and the East of the UK have BTV8, which has never been seen before in Europe, not even in North Africa.”

Bluetongue, which was previously recognised as a sub tropical virus, did hit Cyprus in 1943 and then Portugal and Spain in 1956, where they suffered 200,000 losses, before the virus disappeared three years later.

“We believe the most likely route for the midge into Europe this time was in flowers and fresh produce to air and sea ports, and once here 2006 was exceptionally warm. The midge itself, culicoides, is not new to Europe, but the fact that they carry the virus is.

“They are most active one hour before sunrise and one hour before sunset – and on a dull day they could well be active throughout. It is only the females that bite with activity influenced by temperature – the optimum is 20 – 35 degrees centigrade.”

Jan said in Belgium monitor midge traps have demonstrated that the midge does operate in sheds and not just outside. Once infected by the saliva of the female midge it enters the body of the host and replicates in the blood stream; it depends on whether they make antibodies quickly as to whether they survive.

He said warning signs are not always obvious: “Some animals you see and think will die, but they survive others look ok and two days later they are dead. Symptoms include excessive saliva – forming a white beard, blood in the mucus in the nose, inflammation of the mouth, oedema – a lot of white eye visible, lameness and stiffness, depression and doziness. Loss of appetite, reproductive disorders and secondary infections are also symptomatic.”

Jan Van Grinderachter (right) with retiring chairman, Jim Fleming.

The Belgium, who lost five of his own flock of some 60 ewes, says regular inspection of stock – at least twice a day is imperative. However treatment should not be started until symptoms are seen, because fever is needed to start the immune system. New needles for each case are imperative.

While a small number of whole flocks have been wiped out, many have encountered massive problems with fertility; for Jan’s own flock this means 25 of 48 ewes are not in lamb. In dairy cows it has cost an average of £160 per cow on affected units.

He urged farmers to not get stock too fat and ensure they receive adequate vitamins and minerals to keep the immune system strong: “If they have a reserve of vitamin E and selenium it helps.”

To minimise risk of infection, housing before sunrise and sunset does help, however Jan is sceptical that chemical sprays had been little use, the use of garlic and citronella were not proven either.

He warned: “In 2006, the vector free season in Belgium did not start until December 16, 2006, and it ended on March 30, 2007. The first choice of the midge is cattle and certainly some breeds of sheep are more susceptible than others, Texel being one breed at greater risk.

For this summer what UK farmers need is an inactive vaccine, Europe has banned live vaccine. Furthermore the inactive vaccine can be used at any stage however he warned that it will only last six months, therefore it will be required every year. Although once subjected to the disease animals build their own immunity. However if a different serotype of Bluetongue were to appear a different vaccine would be required.

For more information and a diary of Jan’s first hand experiences in August 2007, visit www.suffolksheep.org "

The farmers Weekly have made a Video about Bluetongue which you can find by the following link.